Borehole logging

Geological structures and characteristics can be “mapped” down an oil well or exploration borehole using active or passive radiation detection and measurement techniques (nuclear logging). Active techniques employ a neutron or gamma source to stimulate gamma rays which, in turn, provide in­formation on the chemical composition, porosity and density of the surrounding rock formation. Conversely, passive techniques measure natural levels of gamma radiation.

Both active and passive logging tools provide valuable data to the oil and minerals exploration industries and are used widely. In particular, the oil well logging industry has been using these techniques for more than 30 years. Data on the porosity and density of rock formations – used to help detect the presence of geological reservoirs and their contents (oil, gas or water) – form one of the “standard” log suites in oil well logging. Moreover, given the vast depth of oil wells and the difficulty in recovering core samples, there are few alternate techniques, thus increasing the oil industry’s reliance on nuclear logging techniques.

Nuclear logging techniques have become more widespread in their application to minerals exploration and analysis outside the oil industry. Nuclear techniques facilitate rapid sampling as well as the sampling of a larger volume of ore due to the depth of penetration of neutrons and gamma rays. Industries within the resources sector where nuclear techniques have particular application include the iron, lead, zinc, nickel and coal industries.

Benefits of SITORO® to borehole logging

Southern Innovation’s SITORO technology is able to operate at radiation count-rates that have not previously been possible; this generates time savings in logging both oil wells and other exploration drill-holes.

A further advantage to the SITORO is the ability to design smaller and lighter tools because the radiation source on a logging tool can be placed closer to the radiation detector; existing oil well logging tools can be in excess of 50ft long and very difficult to manoeuvre in a deep, narrow exploration or production hole.

SITORO also delivers better composition estimates (due to better spectral resolution) and improved statistics from gamma ray events which in turn can improve the accuracy of rock composition or fluid flow estimates.